After very rough anal sex with my partner, my penis is chaffed. is this normal? we did use lube, and are both hiv negative and std free.

Yes: The irritation is due to rubbing, and will heal. Use more lubrication next time.

Irritation: If you have no reason to suspect an std, the most likely culprit is a sensitivity to the specific lubricant you used. This may cause redness, dryness, and itching. If you've used the lubricant before with no issues, it may be due to irritation from simple friction. This should resolve. If it does not go away or if you notice discrete lesions, you should see a physician.

Less is more: The anus is not intended to have a penis in it. It does not produce any significant amount of lubrication. The dry friction rubbing can cause irritation to the skin on the penis. Further more, if there are any nicks or cuts on the penis, stool from your anus can cause severe irritation/burning of the skin. Have him see his doctor. Next time, use lots of lubrication, go slow and finish quickly.